Myopia affects approximately 20% of the population. Flattening the curvature of the front of the eye is a most effective surgical means of correcting myopia. The recent popularization of radial keratotomy for the correction of myopia has made the myopic consumer intensely interested in refractive keratoplasty. Despite insufficient animal experiments and poorly controlled clinical trials, radial keratotomy has become the most commonly performed surgical technique for the correction of myopia. Our preliminary animal studies in rabbits and monkeys have suggested the possibility of long term damage to the corneal endothelium resulting from the radial keratotomy procedure. This endothelial damage may in turn be the cause of disastrous chronic cornial edema and eventual corneal decompensation. We propose to continue and extend these animal studies in order to evaluate the efficacy and safety of radial keratotomy histologicaly and physiologically. Morphological and physiological studies will be conducted on experimental animals over prolonger periods of time to ascertain whether persistent and continuing endothelial damage occurs. Monkeys will be used to assess long term and continuing damage to the corneal endothelium both histologically and in conjunction with the uptake of tritiated thymidine as an indicator of attempted repair. Rabbit corneas that have undergone radial keratotomy will be isolated and used to study endothelial permeability by standard physiological techniques. Corticosteroids will be tested for the ability to prevent or elimnate continuing damage to the endothelium, to ascertain if this damage is related to post-surgical inflammation or to other anatomical or structural changes. Fluorophotometry will be used to study changes in endothelial permeability induced by the radial keratotomy procedure in monkeys and in selected human radial keratotomy patients. Similar physiological and fluorophotometric studies will be done on monkeys that have received epikeratophakia grafts to determine whether nearly doublinig the stromal thickness affects the functioning of the corneal endothelium.